the aims of our research in the coming year are to 1) define the relationship between Ca2 ions and cyclic AMP in cell activation and hormone action; 2) define the metabolism and mode of action of hormones involved in regulating calcium and phosphate metabolism and bone turnover; 3) apply this knowledge to improve diagnosis and therapy of metabolic bone diseases; 4) define the biochemical mode of action of aldosterone and vasopressin upon Na ion and H2O transport in the toad urinary bladder, particularly the relationship between aldosterone-induced changes in phospholipid metabolism and transcellular sodium transport; 5) investigate the role of phospholipids in the expression of membrane-bound enzymatic activities; 6) study the effects of prostaglandins and catecholamines on erythrocyte size, deformability, and osmotic fragility.